The present invention relates to water-absorbing polymer particles which respectively delay the decomposition of body fluids or are antimicrobial; processes for producing such polymer particles; the polymer particles obtainable by these processes, fibers, films, foams or foamed masses comprising such polymer particles; composites comprising such polymer particles; as well as the use of such water-absorbing polymer particles, composite, fibers, films, foams or foamed bodies for producing hygiene and medical articles such as diapers, sanitary napkins or incontinence articles and wound dressings for prevention or treatment of skin irritations arising from excretions and body fluids, preferably nappy rash, as well as for treatment of open wounds.
Through the contact of the skin of the wearer with the excretions and body fluids such as urine and excrement of the wearer which arise when wearing hygiene articles, skin irritations, in particular inflammations, for example the so-called nappy rash, can occur at the body parts covered by the hygiene articles. The occurrence of such skin irritations mostly has as a consequence that the hygiene article can not be worn until the healing of the skin irritation. For the wearer, besides the pain occurring with the skin irritation, a significant loss of mobility and independence is also linked to this.
According to the generally prevailing opinion, such skin irritations are predominantly caused by irritants contained in the urine or excrement of the wearer of a hygiene article, in particular by their decomposition. This can be caused or accelerated by microbes.
Furthermore, besides the particular smell of urine and excrement, further unpleasant odors arise over time, which above all can be linked back to the decomposition thereof. Odors of this type are mostly considered as extremely unpleasant by the wearer and his environment.
In the past, numerous attempts were made to make available water-absorbing polymers which have a delaying effect on the decomposition of body fluids or which contribute to the suppression of the formation of unpleasant odors.
U.S. Pat. No. 6,277,772 B1 teaches the loading of superabsorbing polymer powder, with a size within the range of 100 to 800 μm, with a zeolite powder, which has a particle size within a range between 0.5 and 20 μm and has been charged with antimicrobial cations, for example silver ions. The teaching disclosed in this U.S. patent is disadvantageous, since on the one hand the antimicrobial, water-absorbing polymer must be produced in several steps, and on the other hand, it is disadvantageous that in the contact and the charging with zeolites of the above-mentioned particle size, the danger of dust formation is increased, which increase the health risks both for the workers entrusted with the production of an antimicrobial water-absorbing polymer of this type and for the wearers of hygiene articles comprising these antimicrobial water-absorbing polymers.
WO 01/41819 A1 teaches the use of poorly soluble silver salts or colloidal silver in the production of antimicrobial water-absorbent polymers. Thus, according to this disclosure, colloidal silver or the respective insoluble or poorly soluble silver salts can be added to the monomer solution before the polymerization, or the colloidal silver or the respectively insoluble or poorly soluble silver salts can be applied to the already dried water-absorbing polymer particles. Both process variants are disadvantageous. With the addition of colloidal silver or respectively insoluble or poorly soluble silver salts to the monomer solution, because of the respectively poor solubility or insolubility, a relatively inhomogeneous distribution of the silver salts or of the colloidal silver is obtained. The superficial application of respectively poorly soluble or insoluble silver salts or of colloidal silver leads to these adhering relatively badly to the surface of the water-absorbing polymer particles and mostly further auxiliaries, for example zeolites or surfactants, are necessary for fixing the respectively poorly soluble or insoluble silver salts or the colloidal silver to the surface of the water-absorbing polymer particles. Both the inhomogeneous distribution and the poor surface adhesion lead additionally to an increased separation of respectively silver or silver salts and the water-absorbing polymer particle during transport, storage and in particular the conversion which generates a high mechanical load.
Argyria, permanent dark discoloration of skin caused by overuse of medicinal silver preparations, arising through long exposure of the skin to silver is also generally known. The absorption of silver further leads easily to permanent skin coloration. It results therefrom that also here the surface and inhomogeneous distribution with regions of clearly higher concentration of silver salts or colloidal silver is disadvantageous, since this leads to a higher exposure with the skin surface and thereby increases the risk of an argyria.